
version 1.3
===========
  o modules Hset and Hmap moved into module Hashcons, to avoid the clash with
    a module Hmap from another project (patch from Qi LI)

version 1.2
===========
  o fixed bug in Hset (reported by Jan Midtgaard)

version 1.1
===========
 o do not assume anymore that the hash function returns a nonnegative value

version 1.0, 09/09/2013
=======================
 o code moved to github
